The adversarial system or adversary system is a legal system used in the common law countries where two advocates represent their parties' positions before an impartial person or group of people, usually a jury or judge, who attempt to determine the truth of the case. It is in contrast to the inquisitorial system used in some civil law systems (i.e. those deriving from Roman law or the Napoleonic code) where a judge or group of judges investigates the case.